Double balloon catheter having a lobed inner balloon

ABSTRACT

An apparatus, including a flexible insertion tube having a distal end for insertion into a body cavity, and first and second conduits configured to deliver first and second fluids, respectively, to the distal end. The distal end includes a first balloon coupled to the first conduit so that the first fluid inflates the first balloon and is delivered, via one or more spray ports in the first balloon, to tissue in the body cavity, a second balloon contained within the first balloon and coupled to the second conduit so that the second fluid inflates the second balloon, and multiple splines including a flexible, resilient material and extending along a longitudinal axis of the distal end, and configured to constrain the second balloon so that inflation of the second balloon creates lobes that form, along the longitudinal axis between the lobes, channels that direct the first fluid to the spray ports.

FIELD OF THE INVENTION

The present invention relates generally to invasive probes, andspecifically to an invasive probe configured to irrigate tissue during amedical procedure.

BACKGROUND OF THE INVENTION

A wide range of medical procedures involve placing objects such assensors, tubes, catheters, dispensing devices, and implants, within thebody. An example of a medical procedure that is performed with acatheter is ablation of body tissue such as heart tissue. The ablationmay be used to cure a variety of cardiac arrhythmia, as well as tomanage atrial fibrillation. Such procedures are known in the art. Othermedical procedures using ablation of body tissue, such as treatingvaricose veins, are also known in the art. The ablation energy for theseprocedures may be in the form of radio-frequency (RF) energy, which issupplied to the tissue via one or more electrodes of a catheter used forthe procedures.

The description above is presented as a general overview of related artin this field and should not be construed as an admission that any ofthe information it contains constitutes prior art against the presentpatent application.

Documents incorporated by reference in the present patent applicationare to be considered an integral part of the application except that tothe extent any terms are defined in these incorporated documents in amanner that conflicts with the definitions made explicitly or implicitlyin the present specification, only the definitions in the presentspecification should be considered.

SUMMARY OF THE INVENTION

There is provided, in accordance with an embodiment of the presentinvention, a medical apparatus, including a flexible insertion tubehaving a distal end for insertion into a body cavity, first and secondconduits contained within the flexible insertion tube and configured todeliver first and second fluids, respectively, to the distal end, and aterminal member fixed to the distal end of the insertion tube andincluding a first balloon including one or more spray ports and coupledto the first conduit so that the first fluid inflates the first balloonand is delivered, via the one or more spray ports, to tissue in the bodycavity, a second balloon contained within the first balloon and coupledto the second conduit so that the second fluid inflates the secondballoon, and multiple splines including a flexible, resilient materialand extending along a longitudinal axis of the terminal member, andconfigured to constrain the second balloon so that inflation of thesecond balloon creates lobes that form, along the longitudinal axisbetween the lobes, channels that direct the first fluid from the firstconduit to the one or more spray ports.

In some embodiments, the first fluid includes an irrigation fluid, andthe second fluid includes a contrast agent that can provide radiopacityfor a fluoroscopy unit. In additional embodiments, the medical apparatusaccording may include one or more electrodes mounted on the firstballoon and configured to convey radio-frequency energy to tissue in abody cavity.

In further embodiments the medical apparatus may include a telescopingshaft contained within the second balloon and configured to retract uponinflating the second balloon and to extend upon deflating the secondballoon. In embodiments including the telescoping shaft, the medicalapparatus may include a flexible sleeve surrounding the telescopingshaft and configured to prevent the second fluid from entering theinsertion tube.

In some embodiments, the splines may have cross-sections selected from agroup consisting of rectangular and elliptical cross-sections. Inadditional embodiments, the splines can be embedded in the secondballoon. In further embodiments, the splines can be affixed to an outersurface of the second balloon. In supplemental embodiments, the splinescan be positioned within the second balloon.

There is also provided, in accordance with an embodiment of the presentinvention, a method, including inserting a distal end of flexibleinsertion tube into a body cavity, the flexible insertion tubecontaining first and second conduits configured to deliver first andsecond fluids, respectively, to a terminal member fixed to the distalend of the insertion tube, the terminal member including a first balloonincluding one or more spray ports and coupled to the first conduit, asecond balloon contained within the first balloon and coupled to thesecond conduit, and multiple splines including a flexible, resilientmaterial and extending along a longitudinal axis of the terminal memberand configured to constrain the second balloon. The method also includesconveying, via the first conduit, the first fluid in order to inflatethe first balloon and to deliver, via the one or more spray ports, thefirst fluid to tissue in the body cavity, and conveying, via the secondconduit, the second fluid in order to inflate the second balloon and tocreate, using the splines, lobes on the second balloon that form, alongthe longitudinal axis between the lobes, channels that direct the firstfluid from the first conduit to the one or more spray ports.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method, including providing a medical probe forinsertion into a body cavity, the medical probe including, at its distalend, an outer balloon including one or more spray ports and an innerballoon contained within the outer balloon, injecting a contrast agentinto the inner balloon so as to inflate the inner balloon, visualizingthe distal end of the medical probe in the body cavity by imaging thecontrast agent in the inner balloon, thereby enabling the distal end tobe maneuvered to a target location, and conveying, via the one or morespray ports in the outer balloon, irrigation fluid to tissue at thetarget location.

In some embodiments, the contrast agent provides radiopacity for afluoroscopy unit, and visualizing the distal end may include capturing,by the fluoroscopy unit, an image of the contrast agent in the innerballoon, and presenting the image on a display.

There is further provided, in accordance with an embodiment of thepresent invention, an apparatus, including a medical probe configuredfor insertion into a body cavity and including, at its distal end, anouter balloon including one or more spray ports and an inner ballooncontained within the outer balloon, and a control console configured toinject a contrast agent into the inner balloon so as to inflate theinner balloon, to visualize the distal end of the medical probe in thebody cavity by imaging the contrast agent in the inner balloon, therebyenabling the distal end to be maneuvered to a target location, and toconvey, via the one or more spray ports in the outer balloon, irrigationfluid to tissue at the target location.

There is also provided, in accordance with an embodiment of the presentinvention, a computer software product, operated in conjunction with amedical probe for insertion into a body cavity, the medical probeincluding, at its distal end, an outer balloon including one or morespray ports and an inner balloon contained within the outer balloon, theproduct including a non-transitory computer-readable medium, in whichprogram instructions are stored, which instructions, when read by acomputer, cause the computer, upon injecting a contrast agent into theinner balloon in order to inflate the inner balloon, to visualize thedistal end of the medical probe in the body cavity by imaging thecontrast agent in the inner balloon, thereby enabling the distal end tobe maneuvered to a target location while conveying, via the one or morespray ports in the outer balloon, irrigation fluid to tissue at thetarget location.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic pictorial illustration of a medical systemconfigured to perform an ablation procedure using a double ballooncatheter comprising an inner balloon surrounded by an outer balloon, inaccordance with an embodiment of the present invention;

FIG. 2 is a schematic pictorial illustration of a distal end of thedouble balloon catheter, in accordance with an embodiment of the presentinvention;

FIG. 3 is a schematic cross-sectional longitudinal view of the distalend with the inner balloon in an extended state, in accordance with anembodiment of the present invention;

FIG. 4 is a schematic cross-sectional latitudinal view of the distal endwith the inner and the outer balloons in extended states, in accordancewith an embodiment of the present invention;

FIG. 5 is a schematic cross-sectional longitudinal view of the distalend with the inner and the outer balloons in inflated states, inaccordance with an embodiment of the present invention;

FIG. 6 is a schematic cross-sectional latitudinal view of the distal endwith the inner and the outer balloons in inflated states, in accordancewith an embodiment of the present invention;

FIG. 7 is a schematic detail view showing the outer balloon in contactwith endocardial tissue during an ablation procedure, in accordance withan embodiment of the present invention;

FIG. 8 is a schematic illustration showing a cut-away view of the distalend during the ablation procedure, in accordance with an embodiment ofthe present invention; and

FIG. 9 is a flow diagram that illustrates a method of tracking thedistal end during the ablation procedure, in insertion with anembodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Overview

Various therapeutic procedures such as cardiac ablation use an invasivemedical probe such as a catheter that is inserted into a patient's body.During an ablation procedure on a heart, there may be local overheatingof the heart surface being ablated, as well as of the heart tissueunderlying the surface. The surface overheating may be manifested ascharring, and the overheating of the underlying tissue may cause otherdamage to the tissue, even leading to penetration of the tissue. Tocontrol the temperature of the surface and the underlying tissue, theregion being ablated may be irrigated with an irrigation fluid,typically saline, in order to prevent charring.

In embodiments of the present invention, a medical probe such as acatheter comprises a flexible insertion tube having a distal end forinsertion into a body cavity, and first and second conduits containedwithin the flexible insertion tube and configured to deliver first andsecond fluids, respectively, to the distal end. The medical probe alsocomprises a terminal member that is fixed to the distal end andcomprises a first balloon (also referred to herein as an outer balloon),a second balloon (also referred to herein as an inner balloon) containedwithin the first balloon, and multiple splines that extend along alongitudinal axis of the terminal member. The first balloon comprisesone or more irrigation spray ports and is coupled to the first conduitso that the first fluid inflates the first balloon, and is delivered,via the one or more spray ports, to tissue in the body cavity. Thesecond balloon is coupled to the second conduit so that the second fluidreceived from the second conduit inflates the second balloon. Themultiple splines comprise a shape-memory alloy and extend along alongitudinal axis of the terminal member, so that upon inflating thesecond balloon, the splines constrain the inflation of the secondballoon in order to create lobes that form, along the longitudinal axisbetween the lobes, channels that direct the first fluid from the firstconduit to the one or more spray ports.

In some embodiments, the first fluid may comprise an irrigation fluid.While supplying the outer balloon with the irrigation fluid (i.e., to beconveyed to tissue in a body cavity) during an ablation procedure, theinner balloon can control the overall volume (i.e., of both balloons).Additionally, as described hereinbelow, the inner balloon can beindependently inflated or deflated, thereby significantly shortening theinflation/deflation time of the outer balloon, and reducing the stresson the outer balloon.

In additional embodiments, upon injecting a fluoroscopic contrast agentinto the inner balloon while inflating the inner balloon, the distal endof the medical probe can be visualized fluoroscopically in the bodycavity by imaging the contrast medium in the inner balloon, therebyenabling the distal end to be maneuvered to a target location. Thevisualization of the distal end can be used by an operator while themedical probe conveys, via the one or more spray ports in the outerballoon, irrigation fluid to tissue at the target location.

System Description

FIG. 1 is a schematic pictorial illustration of a medical system 20comprising a medical probe 22 (e.g., a catheter) and a control console24, and FIG. 2 is a schematic illustration of a distal end 26 of themedical probe used in the medical system, in accordance with anembodiment of the present invention. System 20 may be based, forexample, on the CARTO® system, produced by Biosense Webster Inc.(Diamond Bar, Calif., U.S.A.). In embodiments described hereinbelow, itis assumed that probe 22 is used for diagnostic or therapeutictreatment, such as performing ablation of heart tissue in a heart 28.Alternatively, probe 22 may be used, mutatis mutandis, for othertherapeutic and/or diagnostic purposes in the heart or in other bodyorgans.

Probe 22 comprises an insertion tube 30, which an operator 32 insertsinto a lumen, such as a chamber of heart 28, of a patient 34. In theexample shown in FIG. 1, operator 32 inserts insertion tube 30 throughthe vascular system of patient 34 so that a terminal member 36 fixed todistal end 26 enters a chamber of heart 28. Operator 32 can use afluoroscopy unit 38 to visualize distal end 26 inside heart 28.Fluoroscopy unit 38 comprises an X-ray source 40, positioned abovepatient 34, which transmits X-rays through the patient. A flat paneldetector 42, positioned below patient 34, comprises a scintillator layer44 which converts the X-rays which pass through patient 34 into light,and a sensor layer 46 which converts the light into electrical signals.Sensor layer 46 typically comprises a two dimensional array ofphotodiodes, where each photodiode generates an electrical signal inproportion to the light detected by the photodiode.

Control console 24 comprises a processor 48 that converts electricalsignals from fluoroscopy unit 38 into an image 50, which the processorpresents as information regarding the procedure on a display 52. Display52 is assumed, by way of example, to comprise a cathode ray tube (CRT)display or a flat panel display such as a liquid crystal display (LCD),light emitting diode (LED) display or a plasma display. However otherdisplay devices can also be employed to implement embodiments of thepresent invention. In some embodiments, display 52 may comprise atouchscreen configured to accept inputs from operator 32, in addition topresenting image 50.

In the example of FIG. 1, console 24 is connected, via a cable 54, tobody surface electrodes, which typically comprise adhesive skin patches56 that are affixed to patient 34. Processor 48 determines positioncoordinates of distal end 26 inside heart 28 based on impedancesmeasured between patches 56 and one or more electrodes 70 (FIG. 2)mounted on distal end 26. Although the medical system shown in FIG. 1uses impedance-based sensing to measure a location of distal end 26,other position tracking techniques may be used (e.g., magnetic-basedsensors). Impedance-based position tracking techniques are described,for example, in U.S. Pat. Nos. 5,983,126, 6,456,864 and 5,944,022, whosedisclosures are incorporated herein by reference. Magnetic positiontracking techniques are described, for example, in U.S. Pat. Nos.5,391,199, 5,443,489, 6,788,967, 6,690,963, 5,558,091, 6,172,4996,177,792, whose disclosures are incorporated herein by reference. Themethod of position sensing described hereinabove is implemented in theabove-mentioned CARTO™ system and is described in detail in the patentscited above.

Processor 48 typically comprises a general-purpose computer, withsuitable front end and interface circuits for receiving signals fromprobe 22 and controlling the other components of console 24. Processor48 may be programmed in software to carry out the functions that aredescribed herein. The software may be downloaded to console 24 inelectronic form, over a network, for example, or it may be provided onnon-transitory tangible media, such as optical, magnetic or electronicmemory media. Alternatively, some or all of the functions of processor48 may be carried out by dedicated or programmable digital hardwarecomponents.

Based on the signals received from probe 22 and other components ofsystem 20, processor 48 drives display 52 to update image 50 to presenta current position of distal end 26 in the patient's body, as well asstatus information and guidance regarding the procedure that is inprogress. Processor 48 stores data representing image 50 in a memory 58.In some embodiments, operator 32 can manipulate image 50 using one ormore input devices 60. In embodiments, where display 52 comprises atouchscreen display, operator 32 can manipulate image 50 via thetouchscreen display.

As shown in FIG. 2, terminal member 36 comprises an inner balloon 62that is contained within an outer balloon 64, and insertion tube 30comprises an irrigation conduit 66 and an inflation conduit 68 that arecontained within the insertion tube. Irrigation conduit 66 is coupled toouter balloon 64, and enables irrigation fluid to be injected into theouter balloon. Inflation conduit 68 is coupled to inner balloon 62, andenables a fluid separate from the irrigation fluid to be injected intothe inner balloon. In embodiments of the present invention, the fluidinjected into the inner balloon may comprise a contrast-bearing fluid(also referred to herein as a contrast agent. Due to its configuration,medical probe 22 may also be referred to as a double balloon catheter.

In the example shown in FIG. 2, balloons 62 and 64 are inflated, and theouter balloon comprises electrodes 70 that typically comprise one ormore thin metal layers formed over the outer balloon. Although not shownin FIG. 2 (and in FIGS. 3-6) for purposes of simplicity, terminal member36 also comprises wires that convey radio-frequency energy from console24 to electrodes 70, thermocouples that are configured to sensetemperature, and position sensors that can aid navigation of distal end26 in patient 34.

Outer balloon 64 comprises irrigation spray ports 72 that are configuredto convey irrigation fluid from within the outer balloon to tissue in abody cavity such as heart 26 (e.g., during an ablation procedure). Whilethe configuration in FIG. 2 shows irrigation spray ports 72 positionedwithin electrodes 72, positioning each of the irrigation points at anylocation on outer balloon 64 is considered to be within the spirit andscope of the present invention. The configuration of inner balloon 62 isdescribed in the description referencing FIGS. 3 and 4 hereinbelow.

Control console 24 also comprises an ablation module 74, an irrigationmodule 76 and an internal balloon inflation module 78 (also referred toherein as inflation module 78). In operation, ablation module 74monitors and controls ablation parameters such as the level and theduration of ablation power applied to ablation electrodes 70. Irrigationmodule 76 delivers, via irrigation conduit 66, an irrigation fluid toouter balloon 64, and monitors the flow of the irrigation fluid to theouter balloon. The outer balloon conveys irrigation fluid to body cavitytissue via irrigation spray ports 72. Inflation module 78 is configuredto deliver, via inflation conduit 68, an inflation fluid to innerballoon 62 in order to inflate the inner balloon. Inflation module 78 isalso configured to extract the inflation fluid from the inner balloon inorder to deflate inner balloon 62.

The irrigation fluid is typically a saline solution that outer balloondelivers, via irrigation spray ports 72, to tissue in a body cavityduring an ablation procedure in order to prevent charring. In someembodiments of the present invention, the inflation fluid comprises acontrast agent that can be used to enhance contrast of the inner balloonfor medical imaging. For example, the contrast agent may be configuredto provide radiopacity for fluoroscopy unit 38. The contrast agentenables console 24 to present to operator 32, on display 52, innerballoon 62, while outer balloon 64 is performing an ablation procedureand conveying, via the one or more irrigation spray ports, irrigationfluid to tissue in heart 28.

FIG. 3 is a schematic cross-sectional longitudinal view of terminalmember 36 comprising inner balloon 62 and outer balloon 64 in extended(i.e., deflated) states, and FIG. 4 is a schematic cross-sectionallatitudinal view of terminal member 36 with the inner and the outerballoons in extended states in accordance with an embodiment of thepresent invention. For purposes of visual simplicity, electrodes 70 andirrigation spray ports 72 are not shown in FIGS. 3 and 4. Inner balloon62 typically comprises an elastic material such as silicone tubing oranother polymer that is able to stretch while also having the ability torelax to its original (i.e., extended and non-inflated) tubular shape,and outer balloon 62 typically comprises materials such as Pellethane®produced by the Lubrizol Corporation (Wickliffe, Ohio, U.S.A.),polyurethane, Pebax® produced by Arkema S.A. (Colombes, France), nylon,polyethylene terephthalate (PET), or any blend or combination of thesematerials.

In embodiments of the present invention, the inflation of inner balloon62 is constrained by a set of splines 82 that extend longitudinallyabout a telescoping shaft 84 that is enclosed within a thin flexiblesleeve 90. Shaft 84 in turn extends along a longitudinal axis 86 of theterminal member. Telescoping shaft 84 typically comprises aconcertina-like tube that enables the telescoping shaft to retract uponinflating the inner balloon and to extend upon deflating the innerballoon. In the example shown in FIG. 3, inner balloon 62 is deflated,and splines 82 return to their respective original states.

Splines 82 may have elliptical (e.g., circular) or rectangular (that mayappear to be flat) cross-sections, and typically comprise a flexible,resilient material (e.g., a shape-memory alloy such nickel-titanium,also known as Nitinol). In some embodiments, splines 82 may be embeddedwithin the elastic material of the inner balloon, and in alternativeembodiments, the splines can be either affixed to the inner balloon'souter surface (i.e., in between the inner and the outer balloons, asshown in FIG. 4) or affixed to the inner balloon's inner surface (i.e.,in between the inner balloon and sleeve 90). When inner balloon 62 isnot inflated, splines 82 are configured to remain straight (i.e.,respective “original states” for the splines), thus keeping the innerballoon extended, and upon inflating the inner balloon, the rectangularshape of the splines constrains them to bend in a single direction(i.e., outward from longitudinal axis 86). In addition to“straightening” terminal member 36 when inner balloon 62 is notinflated, the shape-memory alloy in splines 82 prevents the terminalmember from “kinking” and therefore malfunctioning due to an errorperformed when manipulating insertion tube 30.

In operation, upon inflating balloons 62 and 64, telescoping shaft 84 isconfigured to retract, and splines 82 are configured to extendlatitudinally in order to create lobes, as described hereinbelow in thedescription referencing FIG. 6. Likewise, upon deflating balloons 62 and64, splines 82 return to their respective original (i.e., straightened)states, thereby extending telescoping shaft 84. While the example inFIG. 3 (and in FIG. 4, as described hereinbelow) shows inner balloon 62in an extended state comprising lobes 88, configuring the inner balloonto have no lobes while the inner balloon is in an extended state isconsidered to be within the spirit and scope of the present invention.Inner balloon 62 is typically more compliant than outer balloon 64,thereby enabling the inner balloon to transition from a “tube” shapewhen not inflated to a spherical shape comprising the lobes describedhereinbelow in the description referencing FIG. 6.

As described supra, telescoping shaft 84 is enclosed within a thinflexible sleeve 90. Sleeve 90 is typically made of silicone or astretchable polymer that surrounds telescoping shaft 84 in order to actas a seal that prevents any back flow of inflation fluid from innerballoon 62 into the telescoping shaft and the bloodstream of thepatient. Sleeve 90 stretches axially and relaxes as the nitinol wiresshift the balloon from extended to inflated states.

As described supra, FIGS. 3 and 4 show terminal member 36 with innerballoon 64 in extended states. In the configuration shown in FIG. 4,inner balloon 62 has an elliptical latitudinal cross-section, and outerballoon 64 comprises lobes 80 that given the outer balloon a “starshaped” latitudinal cross-section. As shown in FIGS. 5 and 6 that aredescribed hereinbelow, upon inflating the inner and the outer balloons,inner balloon 62 inflates to have a star shaped latitudinalcross-section, and outer balloon 64 inflates to have an ellipticallatitudinal cross-section.

FIG. 5 is a schematic cross-sectional longitudinal view of terminalmember 36 comprising balloons 62 and 64 in inflated states, inaccordance with an embodiment of the present invention. In the exampleshown in FIG. 5, telescoping shaft 84 retracts longitudinally andsplines 82 extend latitudinally upon inflating the balloons.

FIG. 6 is a schematic cross-sectional latitudinal view of terminalmember 36 comprising the inner and the outer balloons in inflatedstates, in accordance with an embodiment of the present invention. Asinflation module 78 inflates inner balloon 62 by conveying an inflationfluid 100 to the inner balloon, splines 82 constrain the inflation ofthe inner balloon in order to create lobes 88 that form channels 102(i.e., along longitudinal axis 86 between the lobes) that direct anirrigation fluid 104 from irrigation conduit 66 to irrigation sprayports 72.

Double Balloon Catheter Ablation and Irrigation

FIG. 7 is a schematic detail view showing outer balloon 64 in contactwith endocardial tissue 110 of heart 28 during an ablation procedure,and FIG. 8 is a schematic illustration showing a cut-away view ofterminal member 36 during the ablation procedure, in accordance with anembodiment of the present invention. As described supra, during someelectrophysiological therapeutic procedures, such as cardiac ablation,it is typically important to regulate the temperature of the endocardialtissue. Therefore, during an ablation procedure performed usingelectrodes 70, as shown in FIG. 7, medical probe 22 can irrigateendocardial tissue 110 with irrigation fluid 104, exiting fromirrigation spray ports 72, in order to cool the endocardial tissue andreduce charring. As shown in FIG. 8, inner balloon 62 is inflated withinflation fluid 100 and outer balloon 64 is inflated with irrigationfluid 104.

As described supra, upon inflation module 76 inflating inner balloon 62with inflation fluid 100 and irrigation module 76 inflating outerballoon 64 with irrigation fluid 104, splines 82 extend fromlongitudinal axis 86 in order to create channels 102 (i.e., longitudinaldepressions) on the surface of the inner balloon in order to direct theirrigation fluid to irrigation spray ports 72. Channels 102 aretypically aligned with electrodes 70 in order to optimize flow ofirrigation fluid 104 to irrigation spray ports 72. Additionally,channels 102 prevent the inner and the outer balloons from touching eachother, which can block the delivery of the irrigation fluid to one ormore of the irrigation spray ports. Upon completing the ablationprocedure, inflation module 78 can extract inflation fluid 100 frominner balloon 62 thereby deflating the inner balloon.

FIG. 9 is a flow diagram that illustrates a method of tracking terminalmember 36 during an ablation procedure, in insertion with an embodimentof the present invention. In a first positioning step 120, operator 32manipulates insertion tube 30 so that distal end 26 of medical probe 22enters a chamber of heart 28, and in a first injection step 122,inflation module 78 injects inflation conduit 68 with inflation fluid100 thereby inflating inner balloon 62.

As described supra, inflation fluid may comprise a contrast agent thatprovides radiopacity for fluoroscopy unit 38. In response to fluoroscopyunit 38 imaging the contrast agent in inner balloon 62 and conveying theimage information to console 24, processor 48 presents, in avisualization step 124, image 50 comprising a visualization of distalend 26.

While tracking distal end 26 during a maneuvering step 126, operator 32manipulates insertion tube 30 to maneuver distal end 26 so thatelectrodes 70 engage a target location on endocardial tissue 110, and inan injection step 128, irrigation module 76 injects irrigation fluid 104into insertion tube 30 in order to inflate outer balloon 64 and toconvey, via channels 102 and irrigation spray ports 72, the irrigationfluid to the endocardial tissue. Finally, in an ablation step 130, usingradio-frequency (RF) energy conveyed from ablation module 74, electrodes72 perform an ablation procedure on endocardial tissue 110 whilefluoroscopy unit images the contrast agent (i.e., inflation fluid 100)in the inner balloon and while irrigation spray ports 72 conveyirrigation fluid 104 to the endocardial tissue. In embodiments of thepresent invention, steps 122, 128 and 130 are typically performed inresponse to inputs from operator 32 (e.g., via input devices 60).

It will be appreciated that the embodiments described above are cited byway of example, and that the present invention is not limited to whathas been particularly shown and described hereinabove. Rather, the scopeof the present invention includes both combinations and subcombinationsof the various features described hereinabove, as well as variations andmodifications thereof which would occur to persons skilled in the artupon reading the foregoing description and which are not disclosed inthe prior art.

What is claimed is:
 1. A medical apparatus, comprising: a flexibleinsertion tube having a distal end for insertion into a body cavity;first and second conduits contained within the flexible insertion tubeand configured to deliver first and second fluids, respectively, to thedistal end; and a terminal member fixed to the distal end of theinsertion tube and comprising: a first balloon comprising one or morespray ports and coupled to the first conduit so that the first fluidinflates the first balloon and is delivered, via the one or more sprayports, to tissue in the body cavity; a second balloon contained withinthe first balloon and coupled to the second conduit so that the secondfluid inflates the second balloon; and multiple splines embedded in thesecond balloon, the splines comprising a flexible, resilient materialand extending along a longitudinal axis of the terminal member, andconfigured to constrain the second balloon so that inflation of thesecond balloon creates lobes that form, along the longitudinal axisbetween the lobes, channels that direct the first fluid from the firstconduit to the one or more spray ports.
 2. The medical apparatusaccording to claim 1, wherein the first fluid comprises an irrigationfluid, and wherein the second fluid comprises a contrast agent.
 3. Themedical apparatus according to claim 2, wherein the contrast fluidprovides radiopacity for a fluoroscopy unit.
 4. The medical apparatusaccording to claim 1, and comprising one or more electrodes mounted onthe first balloon and configured to convey radio-frequency energy totissue in a body cavity.
 5. The medical apparatus according to claim 1,and comprising a telescoping shaft contained within the second balloonand configured to retract upon inflating the second balloon and toextend upon deflating the second balloon.
 6. The medical apparatusaccording to claim 5, and comprising a flexible sleeve surrounding thetelescoping shaft and configured to prevent the second fluid fromentering the insertion tube.
 7. The medical apparatus according to claim1, wherein the splines have cross-sections selected from a groupconsisting of rectangular and elliptical cross-sections.
 8. A method,comprising: inserting a distal end of flexible insertion tube into abody cavity, the flexible insertion tube containing first and secondconduits configured to deliver first and second fluids, respectively, toa terminal member fixed to the distal end of the insertion tube, theterminal member comprising: a first balloon comprising one or more sprayports and coupled to the first conduit, a second balloon containedwithin the first balloon and coupled to the second conduit, and multiplesplines embedded in the second balloon, the splines comprising aflexible, resilient material and extending along a longitudinal axis ofthe terminal member and configured to constrain the second balloon;conveying, via the first conduit, the first fluid in order to inflatethe first balloon and to deliver, via the one or more spray ports, thefirst fluid to tissue in the body cavity; and conveying, via the secondconduit, the second fluid in order to inflate the second balloon and tocreate, using the splines, lobes on the second balloon that form, alongthe longitudinal axis between the lobes, channels that direct the firstfluid from the first conduit to the one or more spray ports.
 9. Themethod according to claim 8, wherein the first fluid comprises anirrigation fluid, and wherein the second fluid comprises a contrastagent.
 10. The method according to claim 9, wherein the contrast fluidprovides radiopacity for a fluoroscopy unit.
 11. The method according toclaim 8, and comprising conveying, via one or more electrodes mounted onthe first balloon, radio-frequency energy to tissue in a body cavity.12. The method according to claim 8, and comprising retracting atelescoping shaft contained within the second balloon upon inflating thesecond balloon, and extending the telescoping shaft upon deflating thesecond balloon.
 13. The method according to claim 12, and comprisingpreventing, using a flexible sleeve surrounding the telescoping shaft,the second fluid from entering the insertion tube.
 14. The methodaccording to claim 8, wherein the splines have cross-sections selectedfrom a group consisting of rectangular and elliptical cross-sections.15. A method, comprising: providing a medical probe for insertion into abody cavity, the medical probe comprising, at its distal end, an outerballoon comprising one or more spray ports, an inner balloon containedwithin the outer balloon, and multiple splines embedded in the secondballoon, the splines comprising a flexible, resilient material andextending along a longitudinal axis of the probe, and configured toconstrain the inner balloon so that inflation of the inner ballooncreates lobes that form, along the longitudinal axis between the lobes,channels; injecting a contrast agent into the inner balloon so as toinflate the inner balloon; creating the lobes; visualizing the distalend of the medical probe in the body cavity by imaging the contrastagent in the inner balloon, thereby enabling the distal end to bemaneuvered to a target location; and conveying, via the one or morespray ports in the outer balloon, irrigation fluid to tissue at thetarget location via the channels formed between the lobes.
 16. Themethod according to claim 15, wherein the contrast agent providesradiopacity for a fluoroscopy unit, and wherein visualizing the distalend comprises capturing, by the fluoroscopy unit, an image of thecontrast agent in the inner balloon, and presenting the image on adisplay.
 17. An apparatus, comprising: a medical probe configured forinsertion into a body cavity and comprising, at its distal end, an outerballoon comprising one or more spray ports, an inner balloon containedwithin the outer balloon, and multiple splines embedded in the secondballoon, the splines comprising a flexible, resilient material andextending along a longitudinal axis of the probe, and configured toconstrain the inner balloon so that inflation of the inner ballooncreates lobes that form, along the longitudinal axis between the lobes,channels; and a control console configured: to inject a contrast agentinto the inner balloon so as to inflate the inner balloon, to visualizethe distal end of the medical probe in the body cavity by imaging thecontrast agent in the inner balloon, thereby enabling the distal end tobe maneuvered to a target location, and to convey, via the channelsbetween the lobes and the one or more spray ports in the outer balloon,irrigation fluid to tissue at the target location.
 18. The apparatusaccording to claim 17, wherein the console comprises a display, andcomprising a fluoroscopy unit, wherein the contrast agent providesradiopacity for the fluoroscopy unit, and wherein the console isconfigured to visualize the distal end by capturing, by the fluoroscopyunit, an image of the contrast agent in the inner balloon, and topresent the image on the display.
 19. A computer software product,operated in conjunction with a medical probe for insertion into a bodycavity, the medical probe comprising, at its distal end, an outerballoon comprising one or more spray ports, an inner balloon containedwithin the outer balloon, and multiple splines embedded in the secondballoon, the splines comprising a flexible, resilient material andextending along a longitudinal axis of the probe, and configured toconstrain the inner balloon so that inflation of the inner ballooncreates lobes that form, along the longitudinal axis between the lobes,channels, the product comprising a non-transitory computer-readablemedium, in which program instructions are stored, which instructions,when read by a computer, cause the computer, upon injecting a contrastagent into the inner balloon in order to inflate the inner balloon, tovisualize the distal end of the medical probe in the body cavity byimaging the contrast agent in the inner balloon, thereby enabling thedistal end to be maneuvered to a target location while conveying, viathe channels between the lobes and the one or more spray ports in theouter balloon, irrigation fluid to tissue at the target location.